This application claims the priority of German application 197 20 586.0, filed in Germany on May 16, 1997, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a side impact protection device for an occupant of a vehicle, having an air bag which is divided into two chambers situated above one another by a partition, the lower chamber interacting with a gas generator, and on the partition of the air bag, which, in the inflated condition, is approximately horizontally aligned at least in sections, an oblong primary opening being formed at the end facing away from the gas generator.
German Patent Document DE 44 43 027 A1 shows an air bag for a side impact protection device, in the case of which an approximately horizontal partition arranged in the interior of the air bag divides the air bag into two chambers situated above one another. An inlet opening for the gas flow of a gas generator is provided locally on the lower chamber. On the partition, an approximately rectangular flow-through opening is provided away from the inlet opening, through which flow-through opening, after the inflation of the first chamber, the gas flow can flow into the second chamber situated above the first chamber. On the circumferential side, the horizontal partition is continuously connected with the air bag so that the gas flow can reach the second chamber only through a single flow-through opening. Under unfavorable conditions, it is possible in such an arrangement that, during the inflation of the air bag, because of the contact with the occupant, the single flow-through opening is closed at least partially or almost completely, whereby the lower chamber is then overloaded. This may result in a tearing of a seam or fabric in the lower chamber of the air bag. In contrast, the upper chamber is not filled with gas or is only partially filled with gas, which may impair the optimal functioning of the air bag, mainly if the volume of the upper chamber is approximately equally large or larger than the volume of the lower chamber.
It is an object of the invention improve a partition of an air bag consisting of two adjoining chambers such that an optimal functioning of the two chambers of the air bag is always ensured during the inflation of the air bag.
According to the invention, this and other objects have been achieved by providing an air bag which is divided into two chambers situated above one another by an interior partition, a lower of said chambers communicating with a gas generator, at least a portion of said partition being approximately horizontally aligned in an inflated condition, said partition defining a primary opening communicating said two chambers, said primary opening being situated outside of a radiation area of the gas generator, at least one of said air bag and said partition defining at least one secondary opening communicating said two chambers, said secondary opening being spaced from said primary opening, said secondary opening acting as a pressure relief valve during inflation of the lower chamber of the air bag.
According to the invention, this and other objects have been achieved by providing a method of manufacturing an air bag for a side impact protection device for an occupant of a vehicle, comprising the steps of: attaching first and second layers together at peripheral edges to define an interior space therebetween; attaching an interior partition to each of said layers to divide said interior space into an upper chamber and a lower chamber, said interior partition defining a primary opening communicating said upper and lower chambers, at least one of said air bag and said partition defining at least one secondary opening communicating said upper and lower chambers, said secondary opening being smaller than said primary opening and being spaced from said primary opening, said secondary opening acting as a pressure relief valve during inflation of the lower chamber of the air bag.
The principal advantages achieved by the invention are that as the result of the arrangement of at least one additional opening with a relatively small cross-section on the partition, a pressure relief valve is created when the first chamber is overloaded, which relieves the circumferential seams of the air bag as well as the connecting seams of the partition and the air bag as well as the fabric of the air bag.
According to certain preferred embodiments, the additional opening acting as the pressure relief valve is provided approximately above the gas generator on the lower edge of the folded partition. Furthermore, the end of the partition facing away from the large-surface primary opening ends just before the circumferential seam of the air bag so that an additional opening is formed here between the two superimposed chambers which also operates as a pressure relief valve. Because of the rounded construction of the forward and rearward end of the large-surface primary opening, during the inflation of the air bag, the fabric of the partition and the connecting seam of the two fabric layers of the air bag is protected and no tears will occur in this area.
The end of the partition which extends adjacent to the primary opening is pulled downward in a curved manner, whereby the direction of the gas flow flowing into the second chamber is influenced during the inflation such that the air bag also moves upwards toward the rear in an improved manner.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.